Stator coil including sequentially-connected conductor segments for an electric rotary machine and manufacturing method thereof

ABSTRACT

A tail side coil end includes a plurality of tail conductor pairs sequentially disposed with predetermined radial gaps. The radial gaps between the conductor pairs are widened in the vicinity of their tail joint portions compared with those in the vicinity of the end surface of a stator core. This arrangement effectively prevents adjacent tail joint portions or adjacent slanting portions from undesirably contacting with each other, thereby adequately maintaining electric insulation between the tail conductor pairs and also improving the space factor of the slot.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a stator coil includingserially-connected conductor segments for an electric rotary machine andalso relates to its manufacturing method.

[0002] A conventionally proposed stator coil consists of numerousconductor segments which are inserted into slots of a stator core andserially connected to each other. For example, Japanese Patent No.3118837 discloses a method of manufacturing this type of coil whichincludes U-shaped conductor segments being serially connected.

[0003] According to this kind of serial-joint segmental stator coil, apair of legs of a conductor segment is separately inserted intodifferent slots spaced by an angle equivalent to a pole pitch. Aprotruding part of each leg is bent in the circumferential direction.Then, the distal ends of the legs of different conductor segments aresuccessively joined.

[0004] More specifically, the conductor segment consists of a U-shaped(more accurately, a V-shaped) head conductor portion (also referred toas a curved or turning portions), a pair of in-slot conductor portionsextending from both ends of the head conductor portion and inserted intodifferent slots from one axial side of a core, and a pair of tailconductor portions protruding out of the slots from the other axial sideof the core and extending in the circumferential directions. The distalends of the tail conductor portions of different conductor segments arejoined together. In this specification, the in-slot conductor portionand the tail conductor portion may be collectively referred to as a legof the conductor segment. Accordingly, the head conductor portions ofrespective conductor segments cooperatively constitute a head side coilend. The tail conductor portions of respective conductor segmentscooperatively constitute a tail side coil end.

[0005] Furthermore, Japanese Patent No. 3118837 discloses asmall-turning conductor segment and a large-turning conductor segmentsurrounding the small-turning conductor segment so as to cooperativelyconstitute a conductor segment set. A total of four legs of theconductor segment set are separately held by two rings coaxiallydisposed. A pair of legs of each conductor segment is expanded in thecircumferential direction by causing a relative rotation between tworings to form head slanting portions.

[0006] Furthermore, Japanese Patent Application Laid-open No.2000-139049 discloses a stator core with numerous slots into whichsmall-turning conductor segments and large-turning conductor segmentssurrounding the small-turning conductor segments are inserted so as tocooperatively constitute conductor segment sets. A total of four legs ofthe conductor segment set are separately held by four rings coaxiallydisposed. A pair of legs of each conductor segment is expanded in thecircumferential direction by causing a relative rotation between theserings to form head slanting portions.

[0007] Moreover, Japanese Patent No. 3104700 discloses a process ofwelding a pair of distal end portions of adjacent conductor segmentsdisposed in the radial direction, and also discloses providing anintervening member between two distal end portions of adjacent conductorsegments disposed in the circumferential direction.

[0008] Hereinafter, a conventional method for manufacturing this kind ofserial-joint segmental stator coil disclosed in the above-describedprior art documents will be explained.

[0009] First, a required number of pine-needle shaped conductor segmentsare prepared. Next, each pine-needle shaped conductor segment isconfigured into a U-shaped conductor segment with a pair of in-slotconductor portions angularly spaced by one pole pitch in thecircumferential direction. Then, the U-shaped conductor segments arespatially disposed (more specifically, aligned in the circumferentialdirection) so that a required number of conductor segments aresimultaneously inserted into the slots of the stator core. For theabove-described process, it is possible to use a pair of coaxial ringshaving insertion holes, for example, disclosed in FIG. 3 of JapanesePatent No. 3118837. According to the manufacturing process shown in thisprior art, both legs of a pine-needle shaped conductor segment areseparately inserted into two holes of the coaxial rings which are in thesame angular position. Then, the coaxial rings are mutually rotatedabout their axes by the amount corresponding to one pole pitch in thecircumferential direction. As a result, each pine-needle shapedconductor segment is configured into a U-shaped conductor segment with ahead portion straddling so as to form, as a whole, a U shape (or Vshaped) in the circumferential direction.

[0010] Next, a process of inserting respective conductor segments,formed into a U-shaped configuration and aligned in the circumferentialdirection, into corresponding slots of the core is performed. Thisprocess is performed by pulling the legs out of the rings havinginsertion holes, while holding the head conductor portions of respectiveconductor segments each being formed into a U-shaped configuration andaligned in the circumferential direction, and then inserting the legs ofrespective conductor segments into slots of the core.

[0011] Next, a process for bending each tail conductor portionprotruding out of the slot in the circumferential direction isperformed. Preferably, each tail conductor portion is bent in thecircumferential direction by a half pole pitch. Such circumferentialbending process is performed by using a plurality of coaxial ringshaving insertion holes, for example, disclosed in FIGS. 4 and 5 ofJapanese Patent No. 3196738. The distal ends of respective tailconductor portions are inserted into insertion holes of the coaxialrings. Then, each coaxial ring is rotated in the circumferentialdirection by a half pole pitch (electric angle of π/2), so that eachtail conductor portion is bent in the circumferential direction by ahalf pole pitch. When each coaxial ring is rotated in thecircumferential direction, it is preferable to urge the coaxial ring inthe axial direction so as to advance toward the tail conductor portion.The radius of curvature at the bend point can be enlarged. Next, theprocess of welding the distal end portions of the tail conductorportions is performed according to the predetermined order.

[0012] Through the above-described processes, an endless phase coil, asa coil representing one of the phases, is formed. To form leaderterminals of each phase coil at the head side, one of the U-shaped headconductor portions of the U-shaped conductor segments is cut at anappropriate position. When the leader terminals are formed long enough,the leader portions can be bent in the circumferential direction so asto provide a connecting wire for a neutral point. The reason why suchleader terminals are formed at the head side coil end is to avoid theinterference with the welding operation performed at the tail side coilend.

[0013] The above-described conventional serial-joint segmental statorcoils are preferably used for automotive alternators.

[0014] However, the above-described serial-joint segmental stator coilshave the following problems.

[0015] If other distal end pairs are located closely to distal end pairsto be welded, the other distal end pairs will interfere with the weldingoperation. The welded portion of the distal end pairs will swell in theradial direction. The conductor segments, except the distal end portionsto be welded, are sheathed by an insulation film. Due to welding heat,the insulation film may be softened at the slanting portion locatedclosely to the welded portion. If the insulation film is fused, it willsag downward. The fused insulation film will merge or integrate with aneighboring insulation film. The insulation ability will worsen. Thecoil may cause short-circuit locally.

[0016] Assuring sufficient electric insulation is very important for anautomotive drive motor which incorporates the serial-joint segmentalstator coil to be operated under a high voltage.

[0017] To eliminate of the above-explained problems, it is necessary tosecure sufficient radial gap between adjacent distal end pairs.

[0018] However, according to the above-described arrangements ofconventional serial-joint segmental stator coils, enlarging the radialgap between adjacent distal end pairs will require excessively expandingthe radial pitches of the conductor accommodation positions in the slotcompared with the actual radial size of the in-slot conductor portion.As a result, the space factor of the slot will worsen. The statordiameter will increase. And, the motor size and weight will increase.

SUMMARY OF THE INVENTION

[0019] In view of the foregoing problems of the prior arts, an object ofthe present invention is to provide a stator coil includingserially-connected conductor segments for an electric rotary machinewhich is capable of reducing the motor diameter and the motor weightwhile adequately maintaining electric insulation between distal endportions of the conductor segments to be welded at the tail side coilend.

[0020] To accomplish the above and other related objects, the presentinvention provides a first stator coil including sequentially-connectedconductor segments for an electric rotary machine, including a pluralityof conductor segments accommodated in a slot of a stator core having aneven number of conductor accommodation positions serially aligned in theradial direction, the conductor segments being sequentially connected tocooperatively constitute one turn of a phase coil of an M-phase (M is aninteger not smaller than 3) armature coil. Each of the conductorsegments has a pair of in-slot conductor portions separatelyaccommodated into the conductor accommodation positions of two differentslots mutually spaced by substantially one pole pitch, a head conductorportion continuously extending from the in-slot conductor portions andprotruding from one end of the stator core so as to constitute a headside coil end, and a pair of tail conductor portions continuouslyextending from the in-slot conductor portions and protruding from theother end of the stator so as to constitute a tail side coil end. Thehead conductor portion has a U-shaped head top portion, and a pair ofhead slanting portions extending obliquely in both circumferential andaxial directions from the head top portion and respectively connected tothe in-slot conductor portions. The tail conductor portions has a pairof tail slanting portions extending obliquely in both circumferentialand axial directions from the pair of in-slot conductor portions, andtail joint portions formed at distal ends of the tail slanting portionsand bonded to tail conductor portions of other conductor segment. Thehead side coil end includes a plurality of the head conductor portionsserially disposed in the radial direction when seen from thecircumferential direction. And, the tail side coil end includes aplurality of the tail conductor portions serially disposed in the radialdirection when seen from the circumferential direction. Furthermore, ascharacteristic features of the first stator coil of the presentinvention, the tail side coil end includes a plurality of the tail jointportions disposed serially in the radial direction with predeterminedgaps. And, a radial gap between adjacent tail slanting portions disposedin the radial direction is widened in the vicinity of the tail jointportions compared with a radial gap in the vicinity of an end surface ofthe stator core.

[0021] According to the first stator coil of this invention, at the tailside coil end, the radial gap between adjacent tail joint portions islarger than the radial pitch between the tail slanting portions locatedin the vicinity of the stator core. This arrangement is advantageous inaccommodating a required turn number of conductor segments in the motorhousing without increasing the radial side of the stator core. Itbecomes possible to prevent the tail joint portions or the tail slantportions from undesirably contacting with each other or prevent theelectric insulation from deteriorating. Furthermore, securing asufficient radial pitch between the paired tail joint portionsfacilitates the work for welding and connecting the paired tail jointportions. Furthermore, increasing the gap between the tail slantingportions is advantageous in letting the cooling air flow smoothly. Thestator coil can be cooled effectively.

[0022] Regarding the space for accommodating the coil ends of the statorcore, there is a sufficient idle space at respective radial sides of thetail side coil end. Thus, no problem will arise when the tail slantingportions toward the radially outer side or toward the radially innerside.

[0023] According to the first stator coil of this invention, it ispreferable that a tilt angle of the tail slanting portion positioned ata radially outer side is larger than a tilt angle of the tail slantingportion positioned at a radially inner side, when the tilt angle isdefined as an angle of a line inclined toward the radially outer sidewith respect to an axis of the stator core.

[0024] Tilting the tail slanting portions toward the radially outer sideeasily enlarges the pitches between the tail slanting portions. Themanufacturing method can be simplified.

[0025] According to the first stator coil of this invention, it ispreferable that a tilt angle of the tail slanting portion positioned ata radially inner side is larger than a tilt angle of the tail slantingportion positioned at a radially outer side, when the tilt angle isdefined as an angle of a line inclined toward the radially inner sidewith respect to an axis of the stator core.

[0026] This arrangement brings substantially the same effects as thoseof the above-described arrangement. It is needless to say that thetilting amount can be reduced when the radially outer tail slantingportions are tilted toward the radially outer side while the radiallyinner tail slanting portions are tilted toward the radially inner side.

[0027] In the above-described arrangements, the conductor segment can bereferred to as the later-described conductor segment set.

[0028] According to the first stator coil of this invention, it ispreferable that the tail joint portions of the tail conductor portionsare aligned on a line normal to the axis of the stator core which isspaced from the end surface of the stator core.

[0029] This arrangement makes it possible to sequentially weld thepaired tail joint portions by successively shifting the weldingelectrode in the radial direction. The welding operation can be easilydone. In this case, it is preferable to deform the tail joint portionsso as to protrude in the axial direction.

[0030] According to the first stator coil of this invention, it ispreferable that the tail conductor portions have identical longitudinallength. With this arrangement, it becomes possible to reduce the kindsof necessary conductor segments. Furthermore, the tail joint portions ofthe tail conductor portions are disposed along an arc line. Shifting thewelding electrode along the joint portions is easy.

[0031] According to the first stator coil of this invention, it ispreferable that the tail slanting portions are curved or bent so as tosecure the radial gap between the tail joint portions of the tailconductor portions.

[0032] Namely, the radial gap between the tail slanting portions can begradually increased at a constant rate so that the radial gap linearlyincreases with departing distance from the stator core. Alternatively,it is possible to gradually enlarge the gap increase rate with departingdistance toward the radially outer side. Furthermore, the effect of thefirst stator core defined by this invention can be obtained by largelycurving the tail slanting portions at a predetermined portion toward theradially outer side or the radially inner side.

[0033] The present invention provides a second stator coil includingsequentially-connected conductor segments for an electric rotarymachine, including a plurality of conductor segments accommodated in aslot of a stator core having an even number of conductor accommodationpositions serially aligned in the radial direction, the conductorsegments being sequentially connected to cooperatively constitute oneturn of a phase coil of an M-phase (M is an integer not smaller than 3)armature coil. Each of the conductor segments has a pair of in-slotconductor portions separately accommodated into the conductoraccommodation positions of two different slots mutually spaced bysubstantially one pole pitch, a head conductor portion continuouslyextending from the in-slot conductor portions and protruding from oneend of the stator core so as to constitute a head side coil end, and apair of tail conductor portions continuously extending from the in-slotconductor portions and protruding from the other end of the stator so asto constitute a tail side coil end. The head conductor portion has aU-shaped head top portion, and a pair of head slanting portionsextending obliquely in both circumferential and axial directions fromthe head top portion and respectively connected to the in-slot conductorportions. The tail conductor portions has a pair of tail slantingportions extending obliquely in both circumferential and axialdirections from the pair of in-slot conductor portions, and tail jointportions formed at distal ends of the tail slanting portions and bondedto tail conductor portions of other conductor segment. The head sidecoil end includes a plurality of the head conductor portions seriallydisposed in the radial direction when seen from the circumferentialdirection. And, the tail side coil end includes a plurality of the tailconductor portions serially disposed in the radial direction when seenfrom the circumferential direction. Furthermore, as characteristicfeatures of the second stator coil of the present invention, the tailside coil end includes a plurality of the tail joint portions of thetail conductor portions disposed serially in the axial direction withpredetermined gaps. And, the tail slanting portions are curved or bentat their intermediate points spaced from an end surface of the statorcore so as to extend in the radial direction.

[0034] More specifically, according to the second stator coil of thepresent invention, the tail slanting portions are curved or bentperpendicularly. It is possible to arbitrarily set or determine thepitch between the tail joint portions irrelevant to the radial pitchbetween the in-slot conductor portions accommodated in the slot. As thetail joint portions face the radial outer side or the radial inner side,the welding operation can be done easily. Preferably, the paired tailjoint portions are aligned on a line parallel to the axis of the statorcore.

[0035] Furthermore, the present invention provides a method formanufacturing the above-described stator coil, including the steps ofseparately holding the head top portions of the conductor segmentsinserted in the slots with a plurality of rings disposed coaxially androtatable relative to each other, expanding the tail slanting portionsof the conductor segment in the circumferential direction by rotatingthe rings, deforming the tail conductor portions to incline toward theradially outer side, and welding a pair of the tail joint portionsdisposed adjacently to each other in the radial direction.

[0036] More specifically, according to this manufacturing method of thepresent invention, the tail slanting portions are expanded in thecircumferential direction by using a conventional coaxial rotary ringapparatus as shown in the above-described prior art. Then, respectiveslanting portions held by the stator core are simultaneously tiltedtoward the radially outer side. This simplifies the work for graduallyincreasing the radial pitch between the tail joint portions withdeparting distance from the stator core.

[0037] It is needless to say that the tilt angle of the tail slantingportions toward the radially outer side is dependent on the radialposition of respective tail slanting portions. The tail slanting portionpositioned at the radially outer side has a larger tilt angle.

[0038] Furthermore, the above-described operation for simultaneoustilting the tail slanting portions can be easily performed in thefollowing manner. For example, a truncated cone body placed at theradially inside of the above-described coaxial rotary rings is shiftedin the axial direction toward the stator core. Furthermore, when aplurality of conductor segments (or conductor segment sets) to be tiltedabout the end surface of the stator core is disposed in the radialdirection, the radially outermost tail slanting portion is tilted as afirst step. Then, the next conductor segment (or conductor segment set)neighboring at the radially inner side the outermost one is insertedinto the stator core and is expanded. The tail slanting portion of thenext conductor segment (or conductor segment set) is tilted as a secondstep. In this manner, the slanting portions are successively tilted.

[0039] Furthermore, it is preferable that the operation for simultaneoustilting the tail slanting portions located at radially differentpositions is performed by successively using a plurality of coaxialtruncated cone cylinders having different diameters. The truncated conecylinders can be installed integrally with the above-described coaxialrotary rings. A pair of the truncated cone cylinder and the coaxialrotary ring can be provided for each of the slanting portions located atradially different positions. This effectively prevents the apparatusfrom being complicated.

[0040] Furthermore, the above-described tilting operation and theexpanding operation can be performed simultaneously. Alternatively, theformer operation can be performed first and the latter operation can beperformed next, or vice versa.

[0041] According to the first or second stator coil of the presentinvention, it is preferable that a plurality of conductor segment setsare disposed in the radial direction, each conductor segment set isconstituted by a small-turning conductor segment and a large-turningconductor segment. The small-turning conductor segment includes asmall-turning head portion continuously formed with a pair of thein-slot conductor portions accommodated separately into a pair of theconductor accommodation positions disposed adjacently to each other inthe radial direction. And, the large-turning conductor segment includesa large-turning head portion straddling in the radial direction so as tosurround the small-turning head portion. A group of the conductorsegment sets is located at the same radial position and disposed in thecircumferential direction to constitute a partial phase coil to which apredetermined phase voltage is applied. The phase coil is constituted byserially connecting a plurality of partial phase coils having differentradial positions and disposed sequentially in the radial direction.

[0042] Conventionally, the electric rotary machine using theserial-joint segmental stator coil is used for an automotive alternator.Meanwhile, it is expected that this kind of electric rotary machine isused for an automotive drive motor requiring a large output. To reducethe resistance loss caused in the stator coil and its wiring, it isnecessary to supply an extremely high battery voltage (several hundredsV) to the drive motor. However, there is no substantial difference inthe rotation between the segmental serial-joint type stator coil for adrive motor and the serial-joint segmental stator coil for an automotivealternator. Hence, the turn number of the serial-joint segmental statorcoil for the drive motor must be increased so greatly.

[0043] Increasing the turn number of the serial-joint segmental statorcoil will result in the increase in the wiring resistance. As shown inFIG. 15, the conductor segments 33 a to 33 e are laminated so as to formsurrounded multiple layers of the conductor segments (e.g., 5 layersaccording to the example shown in FIG. 15). When the turn number of theserial-joint segmental stator coil is increased, the number of thein-slot conductor segments disposed in the radial direction in the slotS is increased. According to this kind of multilayered surroundedconductor segments type, many kinds of rounded conductor segments forthe coil end are required by the same number as that of the laminatedlayers. As the outermost rounded conductor segment 33 e becomes long,the overall wiring resistance increases.

[0044] Especially, due to manufacturing reasons, the rounded distal endportion H of the U-shaped conductor segment tends to have a radial widthlarger than that of its proximal end portion L. Although not illustratedin FIG. 15, the actual radial width W of a head side coil end 311becomes large. The axial length of the head side coil end 311 alsobecomes large. The axial length of the motor is increased. The volumeand weight of the motor is increased.

[0045] Furthermore, as described above, the radial width of the distalend portion H of the U-shaped conductor segment becomes larger than thatof the proximal end portion L. To prevent the conductor segments fromcolliding with each other when they are expanded, it is necessary tosecure sufficient clearance d between adjacent conductor segmentsdisposed closely to the proximal end side of the coil end. The spacefactor of the slot will decrease in accordance with the increase of theclearance d.

[0046] Furthermore, the above-described surrounded multilayeredstructure of the conductor segments worsens the heat radiationproperties of the innermost conductor segment 33 a.

[0047] To solve the above-described problems, according to thisarrangement, as shown in FIG. 3, there are provided a plurality ofconductor segment sets disposed in the radial direction, each of whichoccupies four consecutive conductor accommodation positions aligned inthe radial direction in the slot. A predetermined number of conductorsegment sets disposed in the circumferential direction are seriallyconnected to constitute a partial phase coil. The phase coil isconstituted by sequentially connecting the partial phase coils which aredisposed in the radial direction and constituted by a plurality ofconductor segment sets located at different radial positions.

[0048] According to this arrangement, the partial phase coilsneighboring in the radial direction can be easily connected by usingmodified U-shaped conductor segments. Moreover, there is no substantialdifference in the temperature and also in the wiring length between theconductor segment sets (i.e., partial phase coils) located at differentradial positions. The current distribution does not concentrate locally.Excessive heat will not be produced locally. Increasing the turn numberof the coil can be easily realized.

[0049] Furthermore, it is preferable that an inphase slot group isconstituted by a plurality of the slots adjacently and continuouslydisposed in the circumferential direction for accommodating in-slotconductor portions to which the same inphase voltage is applied. Aplurality of serial phase coil circuits are accommodated in differentslots of the inphase slot group, each serial phase coil circuitincluding serially connected partial phase coils accommodated in thesame slot and disposed sequentially in the radial direction to havedifferent radial positions. And, the phase coil is constituted byconnecting the plurality of serial phase coil circuits in parallel witheach other.

[0050] Conventionally, the electric rotary machine using theserial-joint segmental stator coil is used for an automotive alternator.Meanwhile, it is expected that this kind of electric rotary machine isused for an automotive drive motor requiring a large output. Generatinga large output requires a large current. However, there is a limit inincreasing the cross-sectional area of conductor segments for realizingthe required large current. Hence, it is necessary to connect thepartial phase coils in parallel with each other to increase an overallcross-sectional area of the phase coil. However such a parallelconnection requires additional connecting wires and accordingly cannotbe easily realized by sequentially connecting the conductor segments.

[0051] In view of the above, according to this arrangement, the phasecoil is a serial phase coil circuit. There are provided a plurality ofserial phase coil circuits. Each serial phase coil circuit isaccommodated in different slots cooperatively constituting an inphaseslot group. According to this arrangement, it is possible to eliminatethe wiring resistance difference between respective serial phase coilcircuits. Furthermore, it is possible to reduce the current differencebetween respective partial phase coils. Especially, even if there issome resistance difference between the partial phase coils located atdifferent radial positions, the above-described capability ofeliminating the resistance difference between respective serial phasecoil circuits is very important.

[0052] Accordingly, this arrangement makes it possible to increase theturn number of the coil without using numerous kinds of conductorsegments or without adding complicated or special connecting wires.Furthermore, it becomes possible to realize an excellent stator coilpreferably used for an automotive drive motor to be operated under ahigh voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The above and other objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription which is to be read in conjunction with the accompanyingdrawings, in which:

[0054]FIG. 1 is a vertical cross-sectional view showing a drive motorfor an automotive vehicle in accordance with a first embodiment of thepresent invention;

[0055]FIG. 2 is a perspective view schematically showing conductorsegments shown in FIG. 1;

[0056]FIG. 3 is a cross-sectional view partly showing the stator coreshown in FIG. 1, taken along a plane extending in the radial directionof the motor;

[0057]FIG. 4 is a perspective view schematically showing the conditionof conductor segments immediately before they are installed into theslots of the stator core;

[0058]FIG. 5 is a perspective view schematically showing the conditionof conductor segments inserted into rings of a head end twistingapparatus;

[0059]FIG. 6 is a vertical cross-sectional view showing the head endtwisting apparatus;

[0060]FIG. 7 is a vertical cross-sectional view showing a tail endtwisting apparatus;

[0061]FIG. 8 is a plan view showing the tail end twisting apparatus;

[0062]FIG. 9 is a view showing the U-phase wiring pattern of a statorcoil;

[0063]FIGS. 10A and 10B are cross-sectional views partly showing thetail side coil end in accordance with a preferred embodiment of thepresent invention, taken along a plane including the axis of the motor;

[0064]FIGS. 11A and 11B are cross-sectional views partly showing thetail side coil end in accordance with a modified embodiment of thepresent invention, taken along a plane including the axis of the motor;

[0065]FIG. 12 is a cross-sectional view partly showing the tail sidecoil end in accordance with another modified embodiment of the presentinvention, taken along a plane including the axis of the motor;

[0066]FIG. 13 is a cross-sectional view partly showing the tail sidecoil end in accordance with another modified embodiment of the presentinvention, taken along a plane including the axis of the motor;

[0067]FIG. 14 is a cross-sectional view partly showing the tail sidecoil end in accordance with another modified embodiment of the presentinvention, taken along a plane including the axis of the motor; and

[0068]FIG. 15 is a cross-sectional view showing a head side coil end ofa conventional conductor segment set.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] Hereinafter, an electric rotary machine having a stator coilincluding sequentially connected conductor segments and used for ahigh-voltage vehicle in accordance with the present invention will beexplained with reference to the attached drawings. FIG. 1 is across-sectional view showing an electric rotary machine used as a drivemotor for generating a drive power of a vehicle, taken along a planeincluding an axis of this electric rotary machine, although a coil endportion of the stator coil is schematically shown. FIG. 2 is aperspective view showing conductor segments serving as part of a statorcoil. FIG. 3 is a cross-sectional and partial view showing the conditionof conductor segments accommodated in each slot.

Overall Arrangement

[0070] As shown in FIG. 1, the drive motor includes a stator core 1, arotor 2, a stator coil 3, a housing 4, and a rotary shaft 7. The statorcore 1 is fixed on an inner cylindrical wall of the housing 4. Thestator coil 3 is wound in each slot of the stator core 1. The rotor 3 isan IPM type rotor fixed to the rotary shaft 7. The rotary shaft 7 isrotatably supported inside the housing 4. The rotor 3 is disposedradially inside the stator core 1. The stator coil 3 is a three-phasearmature winding. A three-phase inverter, which is connected to anexternal battery of approximately 300V, supplies electric power to thestator coil 3.

[0071] The drive motor is a permanent-magnet type three-phase brushlessDC motor (i.e., synchronous motor) which generates a drive power of asecondary battery vehicle, or a fuel cell powered vehicle, or a hybridvehicle. The rotor structure is replaceable with any other type ofconventionally known synchronous motors, although the explanation for itis omitted in this specification.

Explanation of Stator Coil 3

[0072] The stator coil 3 is constituted by a predetermined number ofconductor segments 33 (i.e., segment set defined in this invention)shown in FIG. 2. Each conductor segment 33, inserted into a slot of thestator core 1 from one side, extends in the slot and protrudes out ofthe stator core 1 from the other side. The protruding portion of theconductor segment 33, having a predetermined length, is twisted in thecircumferential direction by an amount equivalent to an electric angleof π/2. The protruding portions of conductor segments 33 are welded attheir distal ends (i.e., bonding portions) according to predeterminedcombinations. Each conductor segment 33 has an elongated plate bodyconfigured as a whole into U shape which is sheathed by a resin filmexcept the distal ends of the protruding portions, i.e., except thedistal end portions to be welded. This kind of stator coil itself, ascharacterized by sequentially-connected conductor segments, is alreadyknown.

[0073] The detailed arrangement of conductor segment (i.e., segment set)33 is explained hereinafter.

[0074] Each conductor segment (i.e., segment set) 33 consists of a largeconductor segment 331 and a small conductor segment 332, each includinga substantially V-shaped head conductor portion, a pair of in-slotconductor portions, and a pair of protruding tail conductor portions.The in-slot conductor portions extend straight from bifurcated ends ofthe head conductor portion and are accommodated in slots. The protrudingtail conductor portions extend outward from the corresponding in-slotconductor portions. In other words, the stator coil 3 consists of afirst coil end portion (i.e., a head side coil end) 311, a second coilend portion (i.e., a tail side coil end) 312, and the in-slot conductorportion. The first coil end portion 311, formed as a whole into a ringshape, is disposed at one side of the stator core 1. The second coil endportion 312, formed as a whole into a ring shape, is disposed at theother side of the stator core 1. The in-slot conductor portion isdisposed in the slot of the stator core 1.

[0075] Namely, in FIG. 1, the head side coil end 311 is constituted bythe head conductor portions of respective conductor segments 33, whilethe tail side coil end 312 is constituted by the protruding tailconductor portions of respective conductor segments 33.

[0076] As shown in FIG. 1, a total of four groups of segment sets 33 areinserted in one slot and disposed serially in the radial direction. Afirst segment set group S1 is disposed at the innermost side of theslot, when seen in the radial direction. A second segment set group S2is disposed outside of and next to the first segment set S1 when seen inthe radial direction. A third segment set group S3 is disposed outsideof and next to the second segment set S2 when seen in the radialdirection. A fourth segment set group S4 is disposed at the outermostside of the slot, when seen in the radial direction.

[0077] In FIG. 1, reference numeral 3301 represents a head conductorportion of one conductor segment 33 serving as part of the first segmentset group S1, reference numeral 3302 represents a head conductor portionof one conductor segment 33 serving as part of the second segment setgroup S2, reference numeral 3303 represents a head conductor portion ofone conductor segment 33 serving as part of the third segment set groupS3, and reference numeral 3304 represents a head conductor portion ofone conductor segment 33 serving as part of the fourth segment set groupS4.

[0078] The head conductor portions of the first to fourth segment setgroups S1 to S4, disposed serially in the radial direction,cooperatively constitute the above-described head side coil end 311. Forthe purpose of simplifying the drawing, FIG. 1 shows only eight (fourpairs of) tail conductor portions of two segment set groups arranged inthe radial direction at the tail side coil end 312.

Explanation of Conductor Segment 33

[0079] The conductor segment (i.e., segment set) 33 will be explained inmore detail with reference to FIG. 2.

[0080] The conductor segment (i.e., segment set) 33 includes a largeconductor segment 331 (which may be referred to as a large-turningconductor segment) and a small conductor segment 332 (which may bereferred to as a small-turning conductor segment). The large conductorsegment 331 surrounds the small conductor segment 332. The largeconductor segment 331 and the small conductor segment 332 arecollectively referred to as a segment set.

[0081] The large conductor segment 331 consists of a head conductorportion 331 c, a pair of in-slot conductor portions 331 a and 331 b, anda pair of tail conductor portions 331 f and 331 g. The tail conductorportions 331 f and 331 g have distal ends 331 d and 331 e which areportions to be welded. In this respect, the distal ends 331 d and 331 ecan be also referred to as edge portions or joint portions. The in-slotconductor portion 331 a is positioned in the innermost layer andaccordingly may be referred to as the in-slot conductor portion of theinnermost layer. The in-slot conductor portion 331 b is positioned inthe outermost layer and accordingly may be referred to as the in-slotconductor portion of the outermost layer.

[0082] The small conductor segment 332 consists of a head conductorportion 332 c, a pair of in-slot conductor portions 332 a and 332 b, anda pair of tail conductor portions 332 f and 332 g. The tail conductorportions 332 f and 332 g have distal ends 332 d and 332 e which areportions to be welded. In this respect, the distal ends 332 d and 332 ecan be also referred to as edge portions or joint portions. The in-slotconductor portion 332 a is positioned in the inner middle layer andaccordingly may be referred to as the in-slot conductor portion of theinner middle. The in-slot conductor portion 332 b is positioned in theouter middle layer and accordingly may be referred to as the in-slotconductor portion of the outermost middle.

[0083] Regarding the symbol ′ attached to the number in the drawing, itmeans that a portion accompanied by the symbol ′ is identical with theportion denoted by the same reference numeral. Accordingly, in FIG. 2,the joint portions 331 d and 332 d′, which are aligned next to eachother in the radial direction, are welded together. Similarly, the jointportions 332 d and 331 d′, which are aligned next to each other in theradial direction, are welded together. The joint portions 332 e and 331e′, which are aligned next to each other in the radial direction, arewelded together.

[0084] According to FIG. 2, the in-slot conductor portion 331 a of theinnermost layer and the in-slot conductor portion 332 a of the innermiddle layer are accommodated in a predetermined slot of the stator core1. In this case, the other in-slot conductor portion 331 b of theconductor segment 331, positioned in the outermost layer, isaccommodated in a different slot which is angularly offset from that ofthe in-slot conductor portion 331 a by an amount equivalent to apredetermined odd number of pole pitch T (e.g., one magnetic pole pitch(=electric angle of π)). The other in-slot conductor portion 332 b ofthe conductor segment 332, positioned in the outer middle layer, isaccommodated in the same slot as that of the in-slot conductor portion331 b of the conductor segment 331. The head conductor portion 331 c ofthe large conductor segment 331 surrounds the head conductor portion 332c of the small conductor segment 332 in the condition where theconductor segments 331 and 332 are disposed in the slots of stator core1.

Layout of Segment Set in a Slot

[0085]FIG. 3 shows the layout of the segment sets accommodated in theslots of stator core 1.

[0086] Each slot 35 has a total of 16 conductor accommodation positionsP1 to P16 aligned in the radial direction. Only one in-slot conductorportion is placed to each of the conductor accommodation positions P1 toP16. Each slot 35 can receive a total of four segment set groups S1 toS4 serially disposed in the radial direction. The conductoraccommodation positions P1 to P4 are provided for accommodating thein-slot conductor portions of the first segment set group S1. Theconductor accommodation positions P5 to P8 are provided foraccommodating the in-slot conductor portions of the second segment setgroup S2. The conductor accommodation positions P9 to P12 are providedfor accommodating the in-slot conductor portions of the third segmentset group S3. The conductor accommodation positions P13 to P16 areprovided for accommodating the in-slot conductor portions of the fourthsegment set group S4. Each of the segment set groups S1 to S4 consistsof a plurality of conductor segments 33.

[0087] Hereinafter, the detailed explanation will be given withreference to the segment set group S1 located at the innermost side. Thein-slot conductor portion 331 a of the innermost layer is disposed at aradially innermost end of the slot 35 of stator core 1. Disposedradially outer side of the in-slot conductor portion 331 a aresuccessively, in this order, the in-slot conductor portion 332 a of theinner middle layer, the in-slot conductor portion 332 b′ of the outermiddle layer, and the in-slot conductor portion 331 b′ of the outermostlayer. In short, each slot 35 accommodates four in-slot conductorportions of four layers aligned in the radial direction. In FIG. 3, thein-slot conductor portion 332 b′ belongs to a small conductor segment332 which differs from the small conductor segment 332 having thein-slot conductor portion 332 a. Similarly, the in-slot conductorportion 331 b′ belongs to a large conductor segment 331 which differsfrom the large conductor segment 331 having the in-slot conductorportion 331 a. It is needless to say that each of other segment setgroups S2 to S4 has the same layout and arrangement as those of thesegment set group S1. FIG. 4 shows the condition of the conductorsegment (i.e., segment set) 33 consisting of the large conductor segment331 and the small conductor segment 332 which is inserted into the slots35.

Explanation of the Arrangement of Three-Phase Stator Coil

[0088] The segment set groups S1 to S4, each being disposed in a 4-setarrangement in the radial direction, constitute a three-phase statorcoil. FIG. 9 shows the wiring pattern of the U-phase coil serving as apart of the three-phase stator coil.

[0089] There are 9 slots (3 slots×3 phases) per magnetic pole pitch. Thepole number is 12. In other words, a total of 108 slots are provided.Three adjacent slots constitute an inphase slot group to which the sameinphase voltage is applied. As described above, each slot has a total of16 conductor accommodation positions P1 to P16. Only one in-slotconductor portion is accommodated at a corresponding conductoraccommodation position.

[0090] The first segment set group S1, accommodated into the conductoraccommodation positions P1 to P4 which are successive in the radialdirection and disposed from the first to fourth positions when countedfrom the innermost end of the slot, is connected by wave winding so asto constitute three coils per each phase which are respectively referredto as first partial phase coils. FIG. 9 shows the first partial phasecoils U11, U21, and U31. The first partial phase coils U11, U21, and U31are separately accommodated in three different slots disposed adjacentlyto each other and cooperatively constituting an inphase slot group.

[0091] The second segment set group S2, accommodated into the conductoraccommodation positions P5 to P8 which are successive in the radialdirection and disposed from the fifth to eighth positions when countedfrom the innermost end of the slot, is connected by wave winding so asto constitute three coils per each phase which are respectively referredto as second partial phase coils. FIG. 9 shows the second partial phasecoils U12, U22, and U32. The second partial phase coils U12, U22, andU32 are separately accommodated in three different slots disposedadjacently to each other and cooperatively constituting the inphase slotgroup.

[0092] The third segment set group S3, accommodated into the conductoraccommodation positions P9 to P12 which are successive in the radialdirection and disposed from the ninth to twelfth positions when countedfrom the innermost end of the slot, is connected by wave winding so asto constitute three coils per each phase which are respectively referredto as third partial phase coils. FIG. 9 shows the third partial phasecoils U13, U23, and U33. The third partial phase coils U13, U23, and U33are separately accommodated in three different slots disposed adjacentlyto each other and cooperatively constituting the inphase slot group.

[0093] The fourth segment set group S4, accommodated into the conductoraccommodation positions P13 to P16 which are successive in the radialdirection and disposed from the thirteenth to sixteenth positions whencounted from the innermost end of the slot, is connected by wave windingso as to constitute three coils per each phase which are respectivelyreferred to as fourth partial phase coils. FIG. 9 shows the fourthpartial phase coils U14, U24, and U34. The fourth partial phase coilsU14, U24, and U34 are separately accommodated in three different slotsdisposed adjacently to each other and cooperatively constituting theinphase slot group.

[0094] The partial phase coils U11, U12, U13, and U14 are accommodatedin the first slot when counted from one end in the circumferentialdirection, among the three adjacent slots constituting theabove-described inphase slot group. The partial phase coils U21, U22,U23, and U24 are accommodated in the middle slot when counted from oneend in the circumferential direction, among the three adjacent slotsconstituting the above-described inphase slot group. The partial phasecoils U31, U32, U33, and U34 are accommodated in the last slot whencounted from one end in the circumferential direction, among the threeadjacent slots constituting the above-described inphase slot group.

[0095] The partial phase coils U11, U12, U13, and U14 are seriallyconnected in this order to cooperatively constitute a serial phase coilcircuit U1. The partial phase coils U21, U22, U23, and U24 are seriallyconnected in this order to cooperatively constitute a serial phase coilcircuit U2. The partial phase coils U31, U32, U33, and U34 are seriallyconnected in this order to cooperatively constitute a serial phase coilcircuit U3. As conventionally known, the connection for connecting thepartial phase coils serially disposed in the radial direction isperformed by using a modified U-shaped conductor segment inserting intovacant conductor accommodation positions of two partial phase coilsdisposed adjacently to each other in the radial direction.

[0096] For example, a pair of vacant conductor accommodation positionscan be obtained for each partial phase coil by removing an ordinaryconductor segment (preferably, a large-turning conductor segment).Hence, the partial phase coil U12 can be connected to the partial phasecoil U13 by using a modified U-shaped conductor segment inserted at oneend into one of two vacant conductor accommodation positions of thepartial phase coil U12 having been thus obtained and also inserted atthe other end into one of two vacant conductor accommodation positionsof the partial phase coil U13.

[0097] Furthermore, the partial phase coil U12 can be connected to thepartial phase coil U11 by using another modified U-shaped conductorsegment inserted at one end into the other vacant conductoraccommodation position of the partial phase coil U12 and also insertedat the other end into one of two vacant conductor accommodationpositions of the partial phase coil U11.

[0098] A modified conductor segment for a neutral point (or for a leaderterminal) is inserted into the remaining vacant conductor accommodationposition of the partial phase coil U11. Similarly, a modified conductorsegment for a leader terminal (or for a neutral point) is inserted intothe remaining vacant conductor accommodation position of the partialphase coil U14.

[0099] The serial phase coil circuits U1, U2, and U3 are connected atboth ends in parallel with each other so as to constitute the U-phasecoil.

[0100] First explained hereinafter are standard manufacturing processesfor the ordinary stator coil including sequentially-connected conductorsegments. Then, the manufacturing processes in accordance with thisembodiment will follow them.

Standard Head End Twisting Process

[0101] First of all, a required number of two kinds of pine-needleshaped conductor segments, being later expanded into the small conductorsegments 332 and also into the large conductor segments 331, areprepared. Each prepared pine-needle shaped conductor segment has twoelongated legs neighboring to each other and extending straight from itshead being sharply bent. Next, each pine-needle shaped conductor segmentis configured into a U-shaped conductor segment with a pair of in-slotconductor portions angularly spaced by one pole pitch in thecircumferential direction. Then, the U-shaped conductor segments arespatially disposed (more specifically, aligned in the circumferentialdirection) so that a required number of conductor segments aresimultaneously inserted into each slot of the stator core.

[0102] Hereinafter, the process of twisting the head conductor portionwill be explained with reference to FIGS. 5 and 6.

[0103]FIG. 5 shows a condition of the conductor segments not beingcompletely inserted into the twisting apparatus. In FIG. 5, referencenumeral 10 represents a head end twisting apparatus, reference numeral11 represents a small ring, and reference numeral 12 represents a largering. The small ring 11 and the large ring 12 are disposed coaxially androtatable in the circumferential direction to cause an angular shiftbetween them. The small ring 11 has two lines of holes 111 and 112aligned in the circumferential direction at the predetermined pitches.The line of holes 111 is positioned radially inside the line of holes112. Similarly, the large ring 12 has two lines of holes 121 and 122aligned in the circumferential direction at the same pitches as those ofthe holes 111 and 112. The line of holes 121 is positioned radiallyinside the line of holes 122. The holes 111, 112, 121, and 122 arealigned on a radial direction. One of two in-slot conductor portions ofthe large conductor segment (i.e., large-turning conductor segment) 331is inserted into the innermost hole 111, while the other in-slotconductor portion of the large conductor segment 331 is inserted intothe outermost hole 122. One of two in-slot conductor portions of thesmall conductor segment (i.e., small-turning conductor segment) 332 isinserted into the second inner most hole 112, while the other in-slotconductor portion of the small conductor segment 332 is inserted intothe second outermost hole 121.

[0104]FIG. 6 shows a condition of the large conductor segments 331 andthe small conductor segments 332 which are completely inserted into theholes 111, 112, 121, and 122 of the small ring 11 and the large ring 12.As shown in FIG. 6, a head portion pressing plate 16 is disposed axiallyabove the small ring 11 and the large ring 12. The head portion pressingplate 16 is equipped with a pair of claws 160 (although only one claw isshown in the drawing) which is used to clamp the head portions of thelarge conductor segment 331 and the small conductor segment 332 at theirtop from both circumferential sides when these conductor segments 331and 332 are disposed as a pair on the same circumferential position.More specifically, after respective conductor segments 33 are insertedinto the holes 111, 112, 121, and 122, the head portion pressing plate16 is lowered from above. Then, the claws 160 attached beneath the headportion pressing plate 16 clamp the head portions of the paired largeand small conductor segment 331 and 332, disposed at the samecircumferential position, at their top from both circumferential sides.

[0105] Thereafter, the large ring 12 and the small ring 11 are rotatedin circumferential opposed directions by a half pole pitch relative tothe stationary head portion pressing plate 16. With this operation, twolegs of each conductor segment are expanded in the circumferentialdirection to have a circumferential gap equivalent to one pole pitch. Asa result, each of the large conductor segments 331 and the smallconductor segments 332 is configured to have a head conductor portionhaving a U-shaped head top portion, and a pair of head slanting portionsextending obliquely in both circumferential and axial directions fromsaid head top portion and respectively connected to the in-slotconductor portions.

[0106] During the rotation of the rings 11 and 12, the top of the headportion of each conductor segment 33 shifts in the axial directiontoward the rings 11 and 12 in accordance with the rotation of the rings11 and 12. The head portion pressing plate 16 moves in the axialdirection together with the head portions of respective conductorsegments 33. A stopper plate 17 prevents the large conductor segment 331and the small conductor segment 332 from falling deeply. It is possibleto divide the stopper plate 17 into an outer stopper plate and an innerstopper plate. In this case, the outer stopper plate mounts two legspositioned at the radially outer side, while the inner stopper platemounts two legs positioned at the radially inner side. It is preferablethat the inner stopper plate is fixed to the ring 11 and rotatestogether with the ring 11. The outer stopper plate is fixed to the ring12 and rotates together with the ring 12.

[0107] Next, while the head portion pressing plate 16 holds respectiveconductor segments 33, the small ring 11 and the large ring 12 aredisengaged from the conductor segments 33.

Standard Tail Portion Installing Process

[0108] Next, the small U-shaped turning conductor segments 332 arepulled out of the insertion holes of the above-described rings. Asrepresentatively shown in FIG. 4, the small U-shaped turning conductorsegments 332 are installed into the slots 35 of stator core 1 so as tostraddle between a position corresponding to the inner middle layer anda position corresponding to the outer middle layer. Similarly, the largeU-shaped turning conductor segments 331 are pulled out of the insertionholes of the above-described rings. Then, the large U-shaped turningconductor segments 331 are installed into the slots 35 of stator core 1so as to straddle between a position corresponding to the innermostlayer and a position corresponding to the outermost layer. In this case,the small U-shaped turning conductor segments 332 and the large U-shapedturning conductor segments 331 are assembled together with theabove-described head portion pressing plate 16 so that respectiveconductor segments can be installed into corresponding slots 35 at atime. After accomplishing installation of respective conductor segmentsinto the slots 35 of stator core 1, the head portion pressing plate 16is removed.

[0109] The processes of installing the small U-shaped turning conductorsegments 332 and the large U-shaped turning conductor segments 331 intothe slots 35 are not limited to the above-described ones, andaccordingly can be variously modified.

Standard Tail End Twisting Process

[0110] Next, the process for twisting the tail conductor portion of theconductor segment 33 inserted in the slot of the stator will beexplained hereinafter.

[0111] According to this embodiment, the large conductor segment 331includes the outermost layer in-slot conductor portion 331 b and thetail conductor portion 331 g. The tail conductor portion 331 g (whichmay be referred to as an outer layer side end portion), connected to theoutermost layer in-slot conductor portion 331 b, is twisted in apredetermined circumferential direction. Furthermore, the largeconductor segment 331 includes the innermost layer in-slot conductorportion 331 a and the tail conductor portion 331 f. The tail conductorportion 331 f (which may be referred to as an inner layer side endportion), connected to the innermost layer in-slot conductor portion 331a, is twisted in the opposite circumferential direction.

[0112] Similarly, the small conductor segment 332 includes the innermiddle layer in-slot conductor portion 332 a and the tail conductorportion 332 f. The tail conductor portion 332 f (which may be referredto as an inner layer side end portion), connected to the inner middlelayer in-slot conductor portion 332 a, is twisted in the predeterminedcircumferential direction. Furthermore, the small conductor segment 332includes the outer middle layer in-slot conductor portion 332 b and thetail conductor portion 332 g. The tail conductor portion 332 g (whichmay be referred to as an outer layer side end portion), connected to theouter middle layer in-slot conductor portion 332 b, is twisted in theopposite circumferential direction.

[0113] A sum of the circumferential twist amount of the tail conductorportion 331 f and the circumferential twist amount of the tail conductorportion 332 f is equivalent to one pole pitch. A sum of thecircumferential twist amount of the tail conductor portion 331 g and thecircumferential twist amount of the tail conductor portion 332 g isequivalent to one pole pitch.

[0114] The process for twisting the large conductor segment 331 and thesmall conductor segment 332 will be explained in more detail withreference to FIGS. 7 and 8. FIG. 7 is a vertical cross-sectional viewschematically showing a stator coil twisting apparatus 500. FIG. 8 is across-sectional view taken along a line A-A of FIG. 7.

[0115] First, the arrangement of the stator coil twisting apparatus 500will be explained.

[0116] The stator coil twisting apparatus 500 includes a work receiver51 for receiving an outer peripheral portion of the stator core 1, adamper 52 for regulating the movement of stator core 1 in the radialdirection and for holding the stator core 1, a work presser 53 forpreventing the stator core 1 from raising upward, a twist shaping unit54 for twisting the legs of the segment 33 protruding from one end ofthe stator core 1, an elevating shaft 54 a for shifting the twistshaping unit 54 in the axial direction, a plurality of rotary drivingmechanisms 541 a to 544 a for rotating the twist shaping unit 54 in thecircumferential direction, an axial driving mechanism 54 b for shiftingthe elevating shaft 54 a in the axial direction, and a controller 55 forcontrolling each of the rotary driving mechanisms 541 a to 544 a and theaxial driving mechanism 54 b.

[0117] The twist shaping unit 54 includes a total of four cylindricaltwisting jigs 541 to 544 which are coaxially disposed, with their topend surfaces being arranged at the same height. The rotary drivingmechanisms 541 a to 544 a independently rotate the correspondingcylindrical twisting jigs 541 to 544. The axial driving mechanism 54 bshifts the elevating shaft 54 a in the up-and-down direction so that allof the cylindrical twisting jigs 541 to 544 can be integrally raised orlowered.

[0118] As shown in FIG. 8, the twisting jigs 541 to 544 have conductorsegment insertion holes 541 b to 544 b, on their top end surfaces, forreceiving the distal ends (i.e., joint portions) of the tail conductorportions 331 f, 331 g, 332 f, and 332 g of the conductor segment 33inserted into the slots of the stator core 1. The number of conductorsegment insertion holes 541 b to 544 b is equal to the number of theslots 35 of stator core 1. The conductor segment insertion holes 541 bto 544 b are angularly spaced in the circumferential direction atpredetermined intervals so as to correspond to the slots 35 of statorcore 1.

[0119] The conductor segment insertion holes 541 b to 544 b, as shown inFIG. 8, are provided with partition walls 541 c to 544 c, 542 d, and 543d for preventing the conductor segment insertion holes 541 b to 544 bwhich are adjacent to each other in the radial direction fromcommunicating with each other. The thickness of respective partitionwalls 541 c to 544 c, 542 d, and 543 d is determined in the followingmanner. The neighboring partition walls 541 c and 542 c cooperativelyform a gap d1 at the boundary between the outermost layer and the outermiddle layer. The neighboring partition walls 542 d and 543 dcooperatively form a gap d2 at the boundary between the outer middlelayer and the inner middle layer. The neighboring partition walls 543 cand 544 c cooperatively form a gap d3 at the boundary between the innermiddle layer and the innermost layer. The gap d2 is set to be largerthan the gap d1 or the gap d3.

[0120] The stator coil twisting apparatus 500 has the followingfunction.

[0121] The stator core 1, with the conductor segments 33 disposed in itsslots 35, is placed on the work receiver 51. Next, the outer cylindricalwall of the stator core 1 is fixed with the clamper 52. Thereafter, thework presser 53 depresses the upper portion of the stator core 1 as wellas the head conductor portions 331 c of the large-turning conductorsegments 331. Thus, the stator core 1 and the conductor segments 33 aresurely fixed so as not to move in the up-and-down direction.

[0122] After the stator core 1 with the conductor segments 33 installedtherein is fixed by using the damper 52 and the work receiver 53, theelevating shaft 54 a raises the twist shaping unit 54 so that the tailconductor portions 331 f, 331 g, 332 f, and 332 g of respectiveconductor segments 33 are inserted into the conductor segment insertionholes 541 b to 544 b formed in respective twisting jigs 541 to 544.

[0123] The conductor segment insertion holes 541 b to 544 b can receiveonly the distat ends (which later become the joint portions) of tailconductor portions 331 f, 331 g, 332 f, and 332 g of respectiveconductor segments 33. As the tail conductor portions 331 f, 331 g, 332f, and 332 g of respective conductor segments 33 are tapered, they canbe smoothly inserted into the conductor segment insertion holes 541 b to544 b.

[0124] After the tail conductor portions 331 f, 331 g, 332 f, and 332 gof respective conductor segments 33 are inserted into the conductorsegment insertion holes 541 b to 544 b of the twist shaping unit 54, thetwist shaping unit 54 is rotated by the rotary driving mechanisms 541 ato 544 a and raised or lowered by the axial driving mechanism 54 b.

[0125] Hereinafter, rotation of the twist shaping unit 54 is explained.

[0126] The twisting jigs 541 and 543 are rotated in the clockwisedirection by a first angle, while the twisting jigs 542 and 544 arerotated in the counterclockwise direction by a second angle. The firstangle needs not to be equal to the second angle. However, a sum of thefirst angle and the second angle is equal to a required slot pitch.

[0127] Thereafter, the twist shaping unit 54 is rotated by the rotarydriving mechanisms 541 a to 544 a and raised by the axial drivingmechanism 54 b so that the elongated portions of the tail conductorportions 331 f, 331 g, 332 f, and 332 g of respective conductor segments33 extending from the outlet of the slots 35 to the inlet of theconductor segment insertion holes 541 b to 544 b are maintained to havea constant length. In this case, it is preferable that the tailconductor portions 331 f, 331 g, 332 f, and 332 g of respectiveconductor segments 33 rotate and rise so as to trace an arc locus.Considering spring back deformation of respective conductor segments 33,the operation for twisting the tail conductor portions so as to trace anarc locus is performed until the angle exceeds a regulation angleequivalent to a half pole pitch (T/2) by a predetermined amount.

[0128] Thereafter, the axial driving mechanism 54 b and the rotarydriving mechanisms 541 a to 544 a are controlled to rotate the twistshaping unit 54 in the opposite direction and lower it. After finishingthe twisting process of respective conductor segments 33 in this manner,the twist shaping unit 54 is further lowered to remove the tailconductor portions 331 f, 331 g, 332 f, and 332 g of respectiveconductor segments 33 out of the conductor segment insertion holes 541 bto 544 b of the twisting jigs 541 to 544. After the conductor segments33 are removed from the twist shaping unit 54, the rotary drivingmechanisms 541 a to 544 a rotate the twist shaping unit 54 to return itto the original position. Finally, the damper 52 and the work presser 53are disengaged from the stator core 1. Then, the stator with the twistedconductor segments 33 is taken out.

[0129] After all, the above-described twisting process is characterizedby first deforming the tail conductor portions of respective conductorsegments 33 in only the circumferential direction to make the conductorsegments 33 incline in the circumferential direction, then deforming thetail conductor portions of respective conductor segments 33 in both thecircumferential direction and the axial direction to make the conductorsegments 33 incline deeply, and thereafter excessively deforming thetail conductor portions of respective conductor segments 33 in both thecircumferential direction and the axial direction beyond the regulationvalues to make the conductor segments 33 incline excessively, andfinally letting the tail conductor portions of respective conductorsegments 33 return to the regulation values due to self spring backdeformation.

[0130] The twist shaping unit 54 causes the shift movement relative tothe stator core 1 not only the circumferential direction but also in theaxial direction. Hence, it becomes possible to twist the tail conductorportions 331 f, 331 g, 332 f, and 332 g of respective conductor segments33 so as to trace an arc locus, according to which the length of thetail conductor portions 331 f, 331 g, 332 f, and 332 g except for thejoint portions 331 d, 331 e, 332 d, and 332 e can be kept to a constantvalue. In other words, the elongated portions of the tail conductorportions 331 f, 331 g, 332 f, and 332 g of respective conductor segments33 extending from the outlet of the slots 35 to the inlet of theconductor segment insertion holes 541 b to 544 b can be maintained to aconstant length. As a result, it becomes possible to prevent theconductor segments 33 from being pulled out of the conductor segmentinsertion holes 541 b to 544 b.

[0131] Furthermore, only the joint portions 331 d, 332 e, 332 d, and 332e of the conductor segments 33 are inserted into the conductor segmentinsertion holes 541 b to 544 b. As described above, this prevents theconductor segments 33 from being pulled out of the conductor segmentinsertion holes 541 b to 544 b.

Standard Welding Process

[0132] Next, the succeeding standard welding process will be explained.This welding process is substantially the same as the conventional one.

[0133] After the twisting process of the conductor segments isaccomplished, the conductor segment of the innermost layer and theconductor segment of the inner middle layer are welded at their distalends (i.e., the joint portions) as shown in FIGS. 1 and 2. Similarly,the conductor segment of the outermost layer and the conductor segmentof the outer middle layer are welded at their distal ends (i.e., thejoint portions). The stator coil 3 is thus accomplished. The practicalwelding used in this embodiment is, for example, arc welding.

Explanation of Tail Side Coil End 312

[0134] Hereinafter, the configuration of the tail side coil end 312constituting the characteristic part of this embodiment will beexplained. FIGS. 10A and 10B are partly cross-sectional views showingthe tail side coil end 312 in accordance with this embodiment takenalong a plane extending in the radial direction.

[0135] The stator core 1 has an end surface 100 and an inner cylindricalsurface 101. The segment set group S1 is inserted to the radially innerside of each slot 35 and the segment set group S2 is inserted to theradially outer side of each slot 35. One segment set of the segment setgroup S1, positioned at the radially inner side, has a pair of tailconductor pairs 3305 and 3306 protruding out of the stator core 1. Onesegment set of the segment set group S2, positioned at the radiallyouter side, has a pair of tail conductor pairs 3307 and 3308 protrudingout of the stator core 1. These tail conductor pairs 3305, 3306, 3307,and 3308 cooperatively constitute the tail side coil end 312.

[0136] According to the tail side coil end 312 shown in FIG. 10A, thetail conductor pairs 3306 to 3308 inclinedly extend from the end surface100 of the stator core 1 or from the point being slightly offset fromthe end surface 100. The tail conductor pairs 3306 to 3308 inclineradially outward with tilt angles θ2, θ3, and θ4, respectively, withrespect to the axis of the stator coil 1. The tilt angle θ2 is smallerthan the tilt angle θ3. The tilt angle θ3 is smaller than the tilt angleθ4. The tail conductor pairs 3305 to 3308 are substantially identical intheir longitudinal length as shown in FIG. 10A.

[0137] According to the tail side coil end 312 shown in FIG. 10B, thetail conductor pairs 3305 to 3307 inclinedly extend from the end surface100 of the stator core 1 or from the point being slightly offset fromthe end surface 100. The tail conductor pairs 3305 to 3307 inclineradially inward with tilt angles θ2, θ3, and θ4, respectively, withrespect to the axis of the stator coil 1. The tilt angle θ2 is smallerthan the tilt angle θ3. The tilt angle θ3 is smaller than the tilt angleθ4. The tail conductor pairs 3305 to 3308 are substantially identical intheir longitudinal length as shown in FIG. 10B.

[0138] Hereinafter, detailed explanation will be given for the tailconductor pair 3305 as a representative one of the tail conductor pairs3306 to 3308. The tail conductor pair 3305 consists of a pair ofprotruding tail conductor portions overlapped in the radial directionand classified into a tail joint portion 3 c and a tail slanting portion3 d. The tail joint portion 3 c is formed by welding the distal ends ofthe paired protruding tail conductor portions. The tail slanting portion3 d is constituted by the obliquely extending part of the pairedprotruding tail conductor portions. The tail joint portion 3 c does notincline in the circumferential direction when seen from the axialdirection. The tail slanting portion 3 d inclines in the circumferentialdirection when seen from the axial direction. The paired protruding tailconductor portions, constituting the tail slanting portion 3 d, inclinein the circumferentially opposed directions.

[0139] Adopting the above-described arrangement makes it possible tosecure a sufficient radial gap between the tail joint portions 3 cdisposed adjacently to each other in the radial direction, and alsomakes it possible to greatly reduce the radial pitch of the in-slotconductor portions inserted in the slot. As a result, the welding workcan be done easily without lowering the reliability of the weldedportions. The space factor of the slot can be improved. The radial sizeof the stator core can be decreased so as to realize a compact andlight-weight motor.

[0140] Especially, during the work for welding the tail joint portions 3c, the insulation film covering the tail slanting portion 3 d closer tothe tail joint portion 3 c may be heated and softened. However,according to the above-described embodiment, it is possible to secure asufficient radial gap between the tail joint portions 3 c disposedadjacently to each other in the radial direction, at the portion closerto the tail joint portions 3 c. Thus, the above-described embodimentprevents the melted or softened insulation film from deforming to mergewith other insulation film, thereby properly maintaining the electricinsulation between the tail slanting portions 3 d. This is preferable,especially, for the drive motor or other high-voltage motors.

Modified Embodiment

[0141]FIGS. 11A and 11B show a modified embodiment of the presentinvention.

[0142] The embodiments shown in FIGS. 11A and 11B are different fromthose shown in FIGS. 10A and 10B in that the tail joint portions 3 c ofrespective tail conductor pairs 3305 to 3308 are aligned on a line Xnormal to the axis of the stator core 1 which is spaced from the endsurface 100 of the stator core 1. Each tail joint portion 3 c and itsvicinity extend in parallel with the axis of the stator core 1. Thisarrangement is advantageous in facilitating the placement and theshifting movement of a pair of electrodes of the arc welding apparatus.

Modified Embodiment

[0143]FIG. 12 shows another modified embodiment of the presentinvention.

[0144] The embodiment shown in FIG. 12 differs from the embodiment shownin FIGS. 10A and 10B in that each tail slanting portion 3 d is bentperpendicularly at an intermediate point with a predetermined radius ofcurvature and extends outward in the radial direction. Adopting thisarrangement makes it possible to secure a sufficient gap between thetail joint portions 3 c disposed adjacently to each other in the axialdirection. The welding work can be done easily without lowering thereliability of the welded portions.

Modified Embodiment

[0145]FIG. 13 shows another modified embodiment of the presentinvention.

[0146] The embodiment shown in FIG. 13 differs from the embodiment shownin FIG. 12 in that each tail slanting portion 3 d is further bentperpendicularly at another intermediate point so as to extend again inthe axial direction. Adopting this arrangement makes it possible tosecure a sufficient radial gap between the tail joint portions 3 cdisposed adjacently to each other. The welding work can be done easilywithout lowering the reliability of the welded portions. Furthermore,like the embodiments shown in FIGS. 11A and 11B, the tail joint portions3 c can be aligned on a line normal to the axis of the stator core 1.The welding work can be simplified.

Modified Embodiment

[0147] Although not shown in the drawing, it is needless to say thatrespective tail conductor pairs 3305 to 3308 shown in FIGS. 12 and 13can be inclined toward the radially inner side to secure sufficient gapbetween the tail joint portions 3 c, instead of deforming the tailconductor pairs 3305 to 3308 toward the radially outer side.

Modified Embodiment

[0148] It is also possible to deform the tail slanting portion 3 d tohave the tilt angle increasing with departing distance from the endsurface 100 of the stator core 1.

Modified Embodiment

[0149]FIG. 14 shows another modified embodiment of the presentinvention. FIG. 14 shows the developed condition of the tail side coilend 312 prior to the welding operation.

[0150] According to this embodiment, a total of eight pairs of tailconductor pairs 3305 to 3312 constituting a total of four conductorsegment set groups S1 to S4 are serially disposed in the radialdirection.

[0151] According to this embodiment, a pair of edge portions 3 e and 3 fconstitutes the tail joint portion 3 c of respective tail conductorpairs 3305 to 3312. The edge portion 3 e located at the radially innerside protrudes than the other edge portion 3 f located at the radiallyouter side. The edge portion 3 e has a protruding edge being cutobliquely.

[0152] This arrangement brings the effect of facilitating the work forbending respective tail conductor pairs 3305 to 3312 in the radialdirection. More specifically, a sharp edge of a tool can be insertedinto each of recessed spaces a1 to a7 each being provided between a pairof adjacent edge portions 3 e sandwiching the intervening edge portion 3f. The tool is then moved to press any intended protruding edge portion3 e toward the radially outer side. By this shift movement, the edgeportion 3 f is bent together with the neighboring edge portion 3 etoward the radially outer side. Hence, the bending work of respectivetail conductor pairs 3305 to 3312 can be performed easily.

[0153] More specifically, a guide member 4000 having a round chamferedsurface is prepared. The guide member 4000 is placed at the proximal endcorner of the protruding tail conductor pair 3312. The tool edge isinserted into the recessed space a1 and is then raised toward theradially outer side to push the tail joint portion 3 c of the tailconductor pair 3312. While the tail joint portion 3 c of the tailconductor pair 3312 shifts to the radially outer side, the proximal endportion of the tail conductor pair 3312 bends along the round chamferedsurface of the guide member 4000. Next, the guide member 4000 is placedat the proximal end corner of the protruding tail conductor pair 3311.The tool edge is inserted into the recessed space a2 and is then raisedtoward the radially outer side to push the tail joint portion 3 c of thetail conductor pair 3311. While the tail joint portion 3 c of the tailconductor pair 3311 shifts to the radially outer side, the proximal endportion of the tail conductor pair 3311 bends along the round chamferedsurface of the guide member 4000. The bent amount of the tail conductorpair 3311 is set to be smaller than that of the tail conductor pair3312. In the same manner, the tool edge is successively inserted intothe recessed spaces a3 to a7 to accomplish the above-described bendingoperation for each of the remaining tail conductor pairs.

[0154] With the above-described operation, the tail joint portions 3 cof the tail side coil end 312 can be surely and easily spaced from eachother. Preferably, the above-described tool is configured into a sharprod. It is also preferable that the tool has an arc shape so that aplurality of adjacent tail joint portions 3 c can be simultaneously bentto the radially outer side.

Modified Embodiment

[0155] Although the above-described bending operation is performed aftercompleting the tail end twisting operation, it is possible tosimultaneously perform both of the bending operation and the tail endtwisting operation, or perform the bending operation prior to the tailend twisting operation

What is claimed is:
 1. A stator coil including sequentially-connectedconductor segments for an electric rotary machine, comprising: aplurality of conductor segments accommodated in a slot of a stator corehaving an even number of conductor accommodation positions seriallyaligned in the radial direction, said conductor segments beingsequentially connected to cooperatively constitute one turn of a phasecoil of an M-phase (M is an integer not smaller than 3) armature coil,each of said conductor segments having a pair of in-slot conductorportions separately accommodated into the conductor accommodationpositions of two different slots mutually spaced by substantially onepole pitch, a head conductor portion continuously extending from saidin-slot conductor portions and protruding from one end of said statorcore so as to constitute a head side coil end, and a pair of tailconductor portions continuously extending from said in-slot conductorportions and protruding from the other end of said stator so as toconstitute a tail side coil end, said head conductor portion having aU-shaped head top portion, and a pair of head slanting portionsextending obliquely in both circumferential and axial directions fromsaid head top portion and respectively connected to said in-slotconductor portions, said tail conductor portions having a pair of tailslanting portions extending obliquely in both circumferential and axialdirections from said pair of in-slot conductor portions, and tail jointportions formed at distal ends of said tail slanting portions and bondedto tail conductor portions of other conductor segment, said head sidecoil end including a plurality of said head conductor portions seriallydisposed in the radial direction when seen from the circumferentialdirection, and said tail side coil end including a plurality of saidtail conductor portions serially disposed in the radial direction whenseen from the circumferential direction, wherein said tail side coil endincludes a plurality of said tail joint portions disposed serially inthe radial direction with predetermined gaps, and a radial gap betweenadjacent tail slanting portions disposed in the radial direction iswidened in the vicinity of said tail joint portions compared with aradial gap in the vicinity of an end surface of said stator core.
 2. Thestator coil including sequentially-connected conductor segments for anelectric rotary machine in accordance with claim 1, wherein a tilt angleof the tail slanting portion positioned at a radially outer side islarger than a tilt angle of the tail slanting portion positioned at aradially inner side, when said tilt angle is defined as an angle of aline inclined toward the radially outer side with respect to an axis ofsaid stator core.
 3. The stator coil including sequentially-connectedconductor segments for an electric rotary machine in accordance withclaim 1, wherein a tilt angle of the tail slanting portion positioned ata radially inner side is larger than a tilt angle of the tail slantingportion positioned at a radially outer side, when said tilt angle isdefined as an angle of a line inclined toward the radially inner sidewith respect to an axis of said stator core.
 4. The stator coilincluding sequentially-connected conductor segments for an electricrotary machine in accordance with claim 1, wherein said tail jointportions of said tail conductor portions are aligned on a line normal tothe axis of said stator core which is spaced from the end surface ofsaid stator core.
 5. The stator coil including sequentially-connectedconductor segments for an electric rotary machine in accordance withclaim 1, wherein said tail conductor portions have identicallongitudinal length.
 6. The stator coil including sequentially-connectedconductor segments for an electric rotary machine in accordance withclaim 1, wherein said tail slanting portions are curved or bent so as tosecure said radial gap between said tail joint portions of the tailconductor portions.
 7. The stator coil including sequentially-connectedconductor segments for an electric rotary machine in accordance withclaim 1, wherein a plurality of conductor segment sets are disposed inthe radial direction, each conductor segment set is constituted by asmall-turning conductor segment and a large-turning conductor segment,said small-turning conductor segment including a small-turning headportion continuously formed with a pair of said in-slot conductorportions accommodated separately into a pair of said conductoraccommodation positions disposed adjacently to each other in the radialdirection, and said large-turning conductor segment including alarge-turning head portion straddling in the radial direction so as tosurround said small-turning head portion, a group of said conductorsegment sets is located at the same radial position and disposed in thecircumferential direction to constitute a partial phase coil to which apredetermined phase voltage is applied, said phase coil is constitutedby serially connecting a plurality of partial phase coils havingdifferent radial positions and disposed sequentially in the radialdirection.
 8. The stator coil including sequentially-connected conductorsegments for an electric rotary machine in accordance with claim 7,wherein an inphase slot group is constituted by a plurality of saidslots adjacently and continuously disposed in the circumferentialdirection for accommodating in-slot conductor portions to which a sameinphase voltage is applied, a plurality of serial phase coil circuitsare accommodated in different slots of the inphase slot group, eachserial phase coil circuit including serially connected said partialphase coils accommodated in the same slot and disposed sequentially inthe radial direction to have different radial positions, and said phasecoil is constituted by connecting said plurality of serial phase coilcircuits in parallel with each other.
 9. A stator coil includingsequentially-connected conductor segments for an electric rotarymachine, comprising: a plurality of conductor segments accommodated in aslot of a stator core having an even number of conductor accommodationpositions serially aligned in the radial direction, said conductorsegments being sequentially connected to cooperatively constitute oneturn of a phase coil of an M-phase (M is an integer not smaller than 3)armature coil, each of said conductor segments having a pair of in-slotconductor portions separately accommodated into the conductoraccommodation positions of two different slots mutually spaced bysubstantially one pole pitch, a head conductor portion continuouslyextending from said in-slot conductor portions and protruding from oneend of said stator core so as to constitute a head side coil end, and apair of tail conductor portions continuously extending from said in-slotconductor portions and protruding from the other end of said stator soas to constitute a tail side coil end, said head conductor portionhaving a U-shaped head top portion, and a pair of head slanting portionsextending obliquely in both circumferential and axial directions fromsaid head top portion and respectively connected to said in-slotconductor portions, said tail conductor portions having a pair of tailslanting portions extending obliquely in both circumferential and axialdirections from said pair of in-slot conductor portions, and tail jointportions formed at distal ends of said tail slanting portions and bondedto tail conductor portions of other conductor segment, said head sidecoil end including a plurality of said head conductor portions seriallydisposed in the radial direction when seen from the circumferentialdirection, and said tail side coil end including a plurality of saidtail conductor portions serially disposed in the radial direction whenseen from the circumferential direction, wherein said tail side coil endincludes a plurality of said tail joint portions of the tail conductorportions disposed serially in the axial direction with predeterminedgaps, and said tail slanting portions are curved or bent at theirintermediate points spaced from an end surface of said stator core so asto extend in the radial direction.
 10. The stator coil includingsequentially-connected conductor segments for an electric rotary machinein accordance with claim 9, wherein a plurality of conductor segmentsets are disposed in the radial direction, each conductor segment set isconstituted by a small-turning conductor segment and a large-turningconductor segment, said small-turning conductor segment including asmall-turning head portion continuously formed with a pair of saidin-slot conductor portions accommodated separately into a pair of saidconductor accommodation positions disposed adjacently to each other inthe radial direction, and said large-turning conductor segment includinga large-turning head portion straddling in the radial direction so as tosurround said small-turning head portion, a group of said conductorsegment sets is located at the same radial position and disposed in thecircumferential direction to constitute a partial phase coil to which apredetermined phase voltage is applied, said phase coil is constitutedby serially connecting a plurality of partial phase coils havingdifferent radial positions and disposed sequentially in the radialdirection.
 11. The stator coil including sequentially-connectedconductor segments for an electric rotary machine in accordance withclaim 10, wherein an inphase slot group is constituted by a plurality ofsaid slots adjacently and continuously disposed in the circumferentialdirection for accommodating in-slot conductor portions to which a sameinphase voltage is applied, a plurality of serial phase coil circuitsare accommodated in different slots of the inphase slot group, eachserial phase coil circuit including serially connected said partialphase coils accommodated in the same slot and disposed sequentially inthe radial direction to have different radial positions, and said phasecoil is constituted by connecting said plurality of serial phase coilcircuits in parallel with each other.
 12. A method for manufacturing astator coil including sequentially-connected conductor segments for anelectric rotary machine, said stator coil comprising a plurality ofconductor segments accommodated in a slot of a stator core having aneven number of conductor accommodation positions serially aligned in theradial direction, said conductor segments being sequentially connectedto cooperatively constitute one turn of a phase coil of an M-phase (M isan integer not smaller than 3) armature coil, each of said conductorsegments having a pair of in-slot conductor portions separatelyaccommodated into the conductor accommodation positions of two differentslots mutually spaced by substantially one pole pitch, a head conductorportion continuously extending from said in-slot conductor portions andprotruding from one end of said stator core so as to constitute a headside coil end, and a pair of tail conductor portions continuouslyextending from said in-slot conductor portions and protruding from theother end of said stator so as to constitute a tail side coil end, saidhead conductor portion having a U-shaped head top portion, and a pair ofhead slanting portions extending obliquely in both circumferential andaxial directions from said head top portion and respectively connectedto said in-slot conductor portions, said tail conductor portions havinga pair of tail slanting portions extending obliquely in bothcircumferential and axial directions from said pair of in-slot conductorportions, and tail joint portions formed at distal ends of said tailslanting portions and bonded to tail conductor portions of otherconductor segment, said head side coil end including a plurality of saidhead conductor portions serially disposed in the radial direction whenseen from the circumferential direction, and said tail side coil endincluding a plurality of said tail conductor portions serially disposedin the radial direction when seen from the circumferential direction,wherein said tail side coil end includes a plurality of said tail jointportions disposed serially in the radial direction with predeterminedgaps, and a radial gap between adjacent tail slanting portions disposedin the radial direction is widened in the vicinity of said tail jointportions compared with a radial gap in the vicinity of an end surface ofsaid stator core, and a tilt angle of the tail slanting portionpositioned at a radially outer side is larger than a tilt angle of thetail slanting portion positioned at a radially inner side, when saidtilt angle is defined as an angle of a line inclined toward the radiallyouter side with respect to an axis of said stator core, saidmanufacturing method comprising the step of: separately holding saidhead top portions of said conductor segments inserted in said slots witha plurality of rings disposed coaxially and rotatable relative to eachother, expanding said tail slanting portions of said conductor segmentin the circumferential direction by rotating said rings, deforming saidtail conductor portions to incline toward the radially outer side, andwelding a pair of said tail joint portions disposed adjacently to eachother in the radial direction.